The US space agency has its share of unusual jobs, but its latest appeal for participants for a new scientific study is perhaps even more bizarre because the successful applicants will not be required to do anything at all.

For 70 days volunteers will be allowed to read, watch television, take a study course or even carry on with their normal job, and will be paid handsomely for the trouble.

There is, however, one small catch: they won't be allowed to leave their bed – at all – for the entire duration of the ten-week study.

The unusual set of conditions is designed to mimic a long-duration space flight, to help scientists understand how prolonged spells of weightlessness take their toll on the human body.

Participants' beds will be tilted backwards at a six-degree angle, with the head lower than the feet, to prompt cardiovascular stress similar to that experienced by astronauts in space.

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Lying down for such a long period will also cause the volunteers to lose muscle mass and bone density, another major health concern for astronauts spending weeks or months in zero-gravity conditions.

Following their period of bed rest, participants will carry out a series of exercises such as squatting and walking – all while still horizontal – to replicate an astronaut disembarking a lander on another planet and carrying equipment.

Dr Roni Cromwell, senior scientist on the study, told Forbes magazine: "Subjects in the study look at it as a way to help, in that what we eventually do will help astronauts maintain their health while in space."

Any couch potatoes tempted by the idea of becoming an armchair astronaut, however, are advised that they need not apply.

Only volunteers who are "very healthy" will be considered, and will have to pass strict physical tests as well as psychological examinations before they are chosen. to ensure they have the same fitness and mental qualities as an astronaut.